Last week, petitions were presented to the Colorado secretary of state to put a measure on this November’s ballot. There were nearly 160,000 signatures.

The law requires at least 86,105 valid signatures, and the petitioner had hoped for 145,000, since inevitably some signatures will be found invalid by the secretary of state.

Thus it appears a near certainty that Coloradans will get to vote on an amendment to the state constitution designed to “regulate marijuana like alcohol.” It would be taxed, users would have to be 21 or older, and small amounts of home-grown would be legal.

Currently, Colorado allows for “medical marijuana.” The law seems complicated and convoluted to me. But it can’t be that complex, since many of my pot-head friends have medical marijuana cards, and they’ve reached an age where they have trouble figuring out how to use cellphones and MP3 players.

The proposed amendment would eliminate the medical subterfuge, which makes sense. Since Prohibition was repealed nearly 80 years ago, you don’t need a prescription to get a shot of rye. So why should you need a doctor’s note to fill the bowl and light your pipe? After all, aren’t adults capable of making their own decisions?

Republicans have been telling us for years that we’re the best judges of how to spend our own money, and if we decide to buy certain forms of vegetation, shouldn’t that decision be respected?

In general, the Obama administration has agreed to respect local preferences on medical marijuana. But there’s no guarantee that it won’t change policies tomorrow morning — this was, after all, an executive decision, not the legislative result of time-consuming hearings and debates.

And even if Obama remains steadfast on the course of common sense and respecting local policies, he won’t be in office forever. His successor may well reverse course. One can imagine life under a President Rick Santorum, who has his DEA killing dogs and kicking in doors not just for pills and pot, but also to confiscate birth-control medicines and devices.

Making marijuana more legal under Colorado law won’t directly change any of that. Even so, there would be some benefits.

For one thing, various fees and excise taxes levied on legal marijuana should cover enforcement costs, which are now largely a drain. Thus our hard-pressed state treasury would benefit. We’d have more money for schools and parks.

For another, if the state halts enforcement, it sends a message to the feds that it’s time to give up on this moronic war against a plant — a plant that has never killed anyone with an overdose.

Or at least it worked that way during alcohol prohibition, which was supposed to be jointly enforced by the feds and the states. According to “Last Call,” Daniel Okrent’s history of the noble experiment, state and local governments saved money by backing off on enforcement.

New York repealed its prohibition law in 1923. “Repeal only meant that New York police and New York courts, no longer bound by the statute to enforce federal antibooze laws, could hand full responsibility over to Washington.” Massachusetts likewise repealed its state enforcement law.

The feds were overwhelmed, which provided further evidence that Prohibition was a failure. This generated more public pressure for repeal, which finally happened in 1933. So getting Colorado out of this aspect of the war on drugs could be a good first step on a long march toward simple common sense in American drug policy. If the feds think it’s important to protect us from a plant, they can try. There’s no reason for us to waste state resources on such stupidity.

Ed Quillen (ekquillen@gmail.com) of Salida is a weekly contributor to The Denver Post.

Just months ago, Republicans got away with a massive upward redistribution of wealth, raiding $1.5 trillion from the Treasury and sticking future generations with the bill. Now, they're going for more.